Record carrier with two ecc block sizes, and recording method and recorder for recording such record carrier

ABSTRACT

On a small record carrier the inner section of the record carrier represents a significant amount of storage capacity. A regular ECC block however occupies more than one revolution of the record carrier leading to multiplication of burst errors in a single ECC block. By using two ECC block sizes the multiplication of burst errors is prevented. The transition from the small ECC blocks in the inner annular section to the large ECC blocks in the outer annular section of the disk is positioned where one ECC block from the outer annular section occupies one revolution of the record carrier. Thus an optimum division is achieved between large and small ECC blocks optimizing storage capacity and error correction capabilities.

The invention relates to a record carrier comprising a first annularsection with an outer perimeter comprising an first ECC block with asize and a second annular section with an inner perimeter adjacent tothe outer perimeter of the first annular section, the second annularsection comprising a second ECC block with a size where the size of thesecond ECC block is larger than the size of the first ECC block.

Such a record carrier is known from WO01/93262 where a record carrier isdisclosed that comprises annular regions on a circular record carrierwith different size ECC blocks. The objective of WO01/93262 is to usethe available storage capacity of the small record carrier moreefficiently.

This is achieved by reducing the size of ECC blocks in regions wheredata is stored in units smaller than the regular ECC block. An exampleof this is the file system attribute area and linking sectors, whichcontain relatively few bytes. The main file system area is located atthe outer perimeter of the record carrier while a copy of the filesystem area is stored near the center of the record carrier.

The main user data area is located between these two files system areasand uses the regular size ECC blocks.

This record carrier has the disadvantage that the amount of file systeminformation determines the size of the annular region with the smallerECC blocks. The error correction capabilities of the smaller ECC blocksis reduced compared to the larger ECC blocks. The addition of extraerror correction capabilities reduces increases the overhead and reducesthe amount of information that can be stored in the annular region withthe small ECC blocks.

It is an objective of the present invention to use the available area onthe record carrier optimally, yet provide appropriate error correctioncapabilities for the small ECC blocks.

To achieve this objective the record carrier is characterized in thatthe outer perimeter of the first annular section is located where thesize of the second ECC block is equal to a length of the inner perimeterof the second annular section.

When large ECC blocks are used in the first annular section near thecenter of the record carrier one ECC block will occupy more than onerevolution of the record carrier. This can result in two burst errors inthe same ECC block originating from the same surface defect, fingerprint or dust speck.

This effectively halves the error corrective capabilities for the ECCblock. However, if the ECC block size is for instance halved, the errorcorrective capabilities are also halved.

By positioning the transition from the first annular section to thesecond annular section there where exactly one second ECC block fits onthe inner perimeter of the second annular section the area comprisingthe large ECC blocks is as large as possible without invoking reductionsin the error correction capabilities in that section of the recordcarrier.

If the transition would be chosen closer to the center of the recordcarrier the large ECC block would occupy more than one revolution on therecord carrier. This results in an overlap of the ECC block, i.e. asection of the ECC block is directly adjacent to another section of thesame ECC block.

If a fingerprint or dust speck is located in the area of the overlap,the ECC block experiences two burst errors instead of just one. Thisreduces the error correction capabilities of the ECC block.

If the transition would be chosen further away from the center of therecord carrier the inefficiency of the smaller ECC blocks because oftheir smaller size would unnecessarily be expanded into the area of therecord carrier where the larger ECC blocks would provide more efficienterror correction capabilities and would not suffer from the doubling ofthe burst errors because one large ECC block does not occupy more thanone revolution.

Consequently, positioning the transition there where one large ECC blockfits exactly on the inner perimeter of the second annular sectionresults in an optimum balance between error correction capabilities andstorage efficiency.

A further embodiment of the record carrier is characterized in that thefirst ECC block is stored using a first error correcting code and thesecond ECC block is stored using a second error correcting code and thatthe first error correcting code provides a error correction capabilityequal to the second error correcting code.

In order to provide equal error correction capabilities to the first andsecond annular section of the record carrier the small ECC blocks arerecorded using more redundancy because of increased overhead.

This reduces the available storage capacity but this reduction islimited by the optimum choice of the transition from the first annularsection to the second annular section.

A method for recording information on a record carrier comprising thesteps of

-   -   recording an ECC Block in a first annular section with an outer        perimeter using a first ECC block size and    -   recording an ECC block in a second annular section with an inner        perimeter adjacent to the outer perimeter of the first annular        section, using a second ECC block size where the second ECC        block size is larger than the first ECC block size, is        characterized in that the outer perimeter of the first annular        section is located where the second ECC block size is equal to a        length of the inner perimeter of the second annular section.

When large ECC blocks are used in the first annular section near thecenter of the record carrier one ECC block will occupy more than onerevolution of the record carrier. This can result in two burst errors inthe same ECC block originating from the same surface defect, fingerprint or dust speck. This effectively halves the error correctivecapabilities for the ECC block. However, if the ECC block size is forinstance halved, the error corrective capabilities are also halved.

By positioning the transition from the first annular section to thesecond annular section there where exactly one second ECC block fits onthe inner perimeter of the second annular section the area comprisingthe large ECC blocks is as large as possible without invoking reductionsin the error correction capabilities in that section of the recordcarrier.

If the transition would be chosen closer to the center of the recordcarrier the large ECC block would occupy more than one revolution on therecord carrier. This results in an overlap of the ECC block, i.e. asection of the ECC block is directly adjacent to another section of thesame ECC block.

If a fingerprint or dust speck is located in the area of the overlap,the ECC block experiences two burst errors instead of just one. Thisreduces the error correction capabilities of the ECC block

If the transition would be chosen further away from the center of therecord carrier the inefficiency of the smaller ECC blocks because oftheir smaller size would unnecessarily be expanded into the area of therecord carrier where the larger ECC blocks would provide more efficienterror correction capabilities and would not suffer from the doubling ofthe burst errors because one large ECC block does not occupy more thanone revolution.

Consequently, positioning the transition there where one large ECC blockfits exactly on the inner perimeter of the second annular sectionresults in an optimum balance between error correction capabilities andstorage efficiency.

An embodiment of the method is characterized in that the ECC block inthe first annular section is recorded using a first error correctioncode and the ECC block in the second annular section is recorded using asecond error correction code and that the first error correcting codeprovides a error correction capability equal to the second errorcorrection code.

In order to provide equal error correction capabilities to the first andsecond annular section of the record carrier the small ECC blocks arerecorded using more redundancy because of increased overhead.

This reduces the available storage capacity but this reduction islimited by the optimum choice of the transition from the first annularsection to the second annular section.

A recorder for recording information on a record carrier comprising afirst annular section with an outer perimeter comprising an first ECCblock with a size and a second annular section with an inner perimeteradjacent to the outer perimeter of the first annular section, the secondannular section comprising a second ECC block with a size where the sizeof the second ECC block is larger than the size of the first ECC block,the recorder comprising error correction means coupled to processormeans coupled to writing means characterized in that the processor meansis operative to position the outer perimeter of the first annularsection where the second ECC block size is equal to a length of theinner perimeter of the second annular section by providing ECC blocks tothe writing means

When the recorder writes large ECC blocks to the first annular sectionnear the center of the record carrier one ECC block will occupy morethan one revolution of the record carrier. This can result in a playbackdevice, for instance the one incorporated in the recorder, encounteringtwo burst errors when, in the same ECC block originating from the samesurface defect, finger print or dust speck. This effectively halves theerror corrective capabilities of the playback device for correcting theECC block.

However, if the ECC block size is for instance halved as in WO01/93262,the error corrective capabilities are also halved.

When the recorder positions the transition from the first annularsection to the second annular section there where exactly one second ECCblock fits on the inner perimeter of the second annular section, thearea comprising the large ECC blocks is as large as possible withoutinvoking reductions in the error correction capabilities in that sectionof the record carrier.

If the transition would be positioned closer to the center of the recordcarrier by the recorder, the large ECC block would occupy more than onerevolution on the record carrier. This results in an overlap of the ECCblock, i.e. a section of the ECC block is directly adjacent to anothersection of the same ECC block.

If a fingerprint or dust speck is located in the area of the overlap,the ECC block experiences two burst errors instead of just one. Thisreduces the error correction capabilities of the ECC block.

If the recorder would locate the transition further away from the centerof the record carrier the inefficiency of the smaller ECC blocks becauseof their smaller size would unnecessarily be expanded into the area ofthe record carrier where the larger ECC blocks would provide moreefficient error correction capabilities and would not suffer from thedoubling of the burst errors because one large ECC block does not occupymore than one revolution.

Consequently, positioning the transition there where one large ECC blockfits exactly on the inner perimeter of the second annular sectionresults in an optimum balance between error correction capabilities andstorage efficiency.

The processing means provide information to the error correction meansabout where the ECC block will be recorded on the record carrier. Basedon this information the error correction means will apply theappropriate error correcting code to the ECC block and provide the ECCblock comprising the error correction to the processor means, which inturn provides the ECC block to the writing means together with anindication where to record the ECC block on the record carrier. Thewriting means subsequently performs the actual recording of the ECCblock on the indicated position on the record carrier. The recordcarrier for instance comprises a wobble embedded into a groove on therecord carrier to provide addressing information to the writing means.The writing means is thus able to locate the indicated position forrecording on the record carrier.

An embodiment of the recorder is characterized in that the processor arearranged to receive an first ECC block with a first error correctioncode from the error correction means when recording the first ECC blockin the first annular section and processor means is further arranged toreceive a second ECC block with a second error correction code from theerror correction means when recording the second ECC block in the secondannular section and that the error correction capability of the firsterror correction code is equal to the second error correcting code.

In order to provide equal error correction capabilities to the first andsecond annular section of the record carrier the small ECC blocks arerecorded using more redundancy because of increased overhead.

This reduces the available storage capacity but this reduction islimited by the optimum choice of the transition from the first annularsection to the second annular section.

The invention will now be described based on figures.

FIG. 1 shows the overlap and the resulting double burst error in theprior art

FIG. 2 shows the record carrier an ECC block size of the presentinvention.

FIG. 3 shows the division into a first and a second annular section.

FIG. 4 shows a recorder.

FIG. 1 shows the overlap and the resulting double burst error in theprior art. A record carrier 1 comprises an ECC block 2. The ECC block 2is positioned at a certain radius from the center and is longer than acircle at the same radius, i.e. a first section 4 of the ECC block isadjacent to a second section 5 of the ECC block.

A surface contamination or surface damage is located in a region 3covering both sections 4, 5, can result in a burst error in both thefirst section 4 and second section 5. Hence two burst errors will resultin one ECC block.

An error correction code has a certain error correction capability, i.e.the number of correctable errors is limited. If two burst errors occurin an ECC block, the error correction code must handle both burst errorsand hence less error correction capacity remains for other errors in theECC word, compared to the situation that only a single burst erroroccurs.

FIG. 1 shows the ECC block 2 both physically located on the recordcarrier with a circular shape, and as a linear representation showingthe result of the overlap on the location of the burst errors in the ECCblock 2. The first burst error in the first section is located near thestart of the ECC block while the second burst error in the secondsection 5 is located near the end of the ECC block in this example.

FIG. 2 shows the record carrier an ECC block size of the presentinvention. The ECC block 2 in FIG. 2 is of the same size as the ECCblock 2 in FIG. 1 but is located further away from the center of therecord carrier 1. Consequently there is no longer an overlap betweensections of the ECC block 2. A surface contamination 5 or record carrierdamage will no longer cause two burst errors in one ECC block 2 but onlya single burst error in a single section 5 of the ECC block 2, enablingmore errors to be corrected with the same error correcting code.

FIG. 2 shows the situation where the ECC block 2 fits exactly in asingle revolution of the record carrier. A circle 6 indicates theposition on the record carrier where this is the case. ECC blocksoutside this circle 6 are to be recorded using the large ECC block sizewhile ECC blocks inside the circle 6 are to be recorded using the smallECC block size. This allows the prevention of the formation of doubleburst errors by a single surface contamination or record carrier damage.The small ECC blocks recorded inside the circle 6 can be protected usingan error correction code which offers better error correctioncapabilities. A proposal for this error correction code is outlinedbelow under ‘Dual format ECC error correction implementation’.

FIG. 3 shows the division into a first and a second annular section. Itis desirable to store as much data on a record carrier as possible.Limitations to the amount of data which can be stored on a recordcarrier are the data density, the maximum outer diameter of thewriteable area and the minimum inner diameter of the writeable area. Themaximum outer diameter is limited by the diameter of the record carrier.The minimum inner diameter is limited by the clamping area needed toclamp the record carrier on the spindle. For a given record carrier sizewith a given data density it is thus desirable to record as close aspossible to the center of the record carrier. This is especially truefor record carriers with a small diameter. While on a regular DVD, Bluedisc or CD the inner section close to the clamping are can be neglectedsince any gain represents a small percentage of record carrier storagecapacity. On a small disc however the inner section close to theclamping area represents a significant percentage of the total recordcarrier storage capacity.

In FIG. 3 the record carrier 1 comprises a first annular section 8 and asecond annular section 7. The first annular section 8 has an innerperimeter and an outer perimeter 6. The second annular section 7 has aninner perimeter essentially coinciding with the outer perimeter of thefirst annular section. Because the ECC block size in the first annularsection 8 is smaller than the ECC block size in the second annularsection 7 a transition from the first annular section 8 to the secondannular section 7 exists this transition can be an abrupt change in ECCblock size from one ECC block to another ECC block or can be implementedwith an intermediate area which can for instance be left empty. It isthus not essential for the invention that the two annular sections 7, 8are directly adjacent but in order to maximize the use of the recordingarea the transition from the first section 8 to the second section 7should be minimized.

FIG. 4 shows a recorder.

The recorder 30 comprises an interface 32 for receiving commands anddata from other devices or higher-level applications, and for providingdata from the record carrier and messages from the recorder to otherdevices and higher-level applications. The interface 32 is coupled to aprocessor 31 which can be implemented as a micro controller, amicroprocessor, or a gate array. The processor 31 handles various tasksof the recorder, for instance data processing, command parsing andcontrol of the basic bit engine 33 and interfacing with the operator viaa keyboard and display (not shown). The processor 31 also coordinatesthe application of the error correction code to the ECC blocks. For thispurpose two-error correction means 35, 36 are indicated in FIG. 4. Eacherror correction means is arranged for providing an error correctioncode to an ECC block. Depending on where the ECC Block will be writtenon the record carrier the processor will provide the data for the ECCblock to one of the error correction means 35, 36. The error correctionmeans then applies the error correction code to the data and provides anECC block back to the processor 31. The processor 31 then instructs thewriting means, i.e. the basic bit engine 33 to write the ECC block atthe specified address on the record carrier 34. In this way theprocessor can control the size and error correction code of the ECCblocks in the annular sections of the record carrier 34. It is selfevident that the error correction means 35, 36 can be implemented in theprocessor 31 in software or hardware, instead of external to theprocessor 31. Also a single error correction means able to apply botherror correction codes to data blocks can be used instead of two errorcorrection means 35,36.

Dual Format ECC Error Correction Implementation

The ECC scheme that can be employed contains two types of ECC blocks:

-   1. The Blu-ray Disc error correction block-   2. An error correction block that is shorter than the first one can    contain 32 Kbytes of data, with more overhead than the first one,    but with similar error correction capabilities.

The first ECC block is used at the outer side of the disc, the secondECC block at the inner side of the disc. The switch takes place at theradius where the circumvention of the disc is equal to the length of oneBlu-ray Disc ECC block.

Inner Radius ECC Block Description

The terminology used is similar to the terminology used in the Blu-rayDisc system description.

The frames of the new error correction format are equal to the frames inthe BD error correction format: 152 LDC bytes and 3 BIS-bytes.

Data Block:

The data block is formed by putting 16 data frames of 2052 bytes eachinto a 304×108 matrix: 304 columns 0 1 . . . 18 19 . . . 37 38 . . . 303108 d_(0,0) d_(108,0) . . . d_(1944,0) d_(0,1) . . . d_(1944,1) d_(0,2). . . d_(1944,15) rows d_(1,0) d_(109,0) . . . d_(1945,0) d_(1,1) . . .d_(1945,1) d_(1,2) . . . d_(1945,15) . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . d_(107,0) e_(215,0) . . . d_(2051,0) d_(107,1) .. . d_(2051,1) d_(107,2) . . . d_(2051,15)LDC Block:

The LDC block is formed by adding 32 parity symbols to each column ofthe Data block. 304 columns codeword 0 codeword 1 . . . codeword L . . .codeword 302 codeword 303 1 LDC 108 e_(0,0) e_(0,1) . . . e_(0,L) . . .e_(0,302) e_(0,303) codeword = rows e_(1,0) e_(1,1) . . . e_(1,L) . . .e_(1,302) e_(1,303) 140 bytes with e_(2,0) . . . . . . . . . . . . . . .. . . data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . e_(107,0) e_(107,1) . . . e_(107,L) . . .e_(107,302) e_(107,303) 32 p108,0 p108,1 . . . p108,L . . . P108,302p108,303 rows . . . . . . . . . . . . . . . . . . . . . with . . . . . .. . . . . . . . . . . . . . . parity . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . P139,0 p139,1 . . .P139,L . . . P139,302 p139,303An LDC-cluster is formed from this LDC block in two interleaving steps:First Interleaving Step:

In the first interleaving step two columns of the LDC Data block aremerged in to one column of the LDC cluster in the following way: 152columns 0 1 . . . . . . 151 216 e_(0,0) e_(0,2) . . . . . . e_(0,302)279 rows . . . . . . rows with e_(1,0) e_(1,2) . . . . . . e_(1,302)data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . e_(107,0) e_(107,2) . . . . . . e_(107,302) 63 p108,0 p108,2 . . . .. . e_(108,302) rows . . . . . . with . . . . . . . . . . . . . . .parity . . . . . . . . . . . . . . . P138,0 P138,2 . . . . . .e_(138,302) . . . . . . P139,0 P139,2 . . . . . . e_(139,302)Note that the last symbol of each odd codeword of the LDC block is notused!Second Interleaving StepIn the second interleaving step the rows are shifted cyclically to theleft in groups of two rows. The shift is increased by 3 for each groupof rows, starting with shift 0 for the first two rows. This is almostequal to the second interleaving step of the BD format.BIS—ColumnsEach row of the ECC block contains 3 BIS-columns. The 279 rows of theECC block are divided into 9 addressing units of 31 rows each. The firstthree rows of each unit in the BIS-cluster contain the 9-byte Addressfields. The remaining rows contain the user control bytes (UC-bytes,16×18 bytes) and the parity bytes (18×26 bytes).

User Control Data Units: 16 units 0 1 . . . S . . . 31 18 bytes UC_(0,0)UC_(0,1) . . . UC_(0,S) . . . UC_(0,31) UC_(1,0) UC_(1,1) . . . . . . .. . UC_(1,31) . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . UC_(17,0) UC_(17,1) . . . UC_(17,S) . . . UC_(17,31)

Address Fields: 9 addresses 0 1 . . . S . . . 8 9 bytes AF_(0,0)AF_(0,1) . . . AF_(0,S) . . . AF_(0,31) . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . AF_(8,0) AF_(8,1) . . . AF_(8,S). . . AF_(8,31)The BIS-columns are formed by interleaving nine RS (47,21,27) codewords(0 . . . 8) and nine RS (46,20,27) codewords (9 . . . 17):

BIS-cluster:

3 BIS → columns 0 1 2 ↑ ↑ b_(x,0) b_(x,1) b_(x,2) b_(x,3) b_(x,4)b_(x,5) : : : : : : 31 : : : rows b_(x,15) b_(x,16) b_(x,17) (A.U.)b_(x,0) b_(x,1) b_(x,2) : : : : : : ↓ b_(x,0) b_(x,1) b_(x,2) ↑ b_(x,3)b_(x,4) b_(x,5) 9 : : : address 31 : : : units rows : : : = (A.U.) : : :279 : : : rows ↓ : : : : : : : : : : : : : : : ↑ : : : : : : 31 : : :rows : : : : : : ↓ ↓ b_(x,6) b_(x,7) b_(x,8)In each address unit, the rows will be shifted cyclically to the left ingroups of three rows. For each subsequent group the shift is increasedby 1, starting with shift 0 for the first group of three rows. Note thatthis shift is not shown in the figure of the BIS-cluster.

1. Record carrier comprising a first annular section with an outerperimeter comprising an first ECC block with a size and a second annularsection with an inner perimeter adjacent to the outer perimeter of thefirst annular section, the second annular section comprising a secondECC block with a size where the size of the second ECC block is largerthan the size of the first ECC block, characterized in that the outerperimeter of the first annular section is located where the size of thesecond ECC block is equal to a length of the inner perimeter of thesecond annular section.
 2. Record carrier as claimed in claim 1,characterized in that the first ECC block is stored using a first errorcorrection code and the second ECC block is stored using a second errorcorrection code and that the first error correction code provides aerror correction capability equal to the second error correction code.3. Method for recording information on a record carrier comprising thesteps of recording an ECC Block in a first annular section with an outerperimeter using a first ECC block size and recording an ECC block in asecond annular section with an inner perimeter adjacent to the outerperimeter of the first annular section, using a second ECC block sizewhere the second ECC block size is larger than the first ECC block size,characterized in that the outer perimeter of the first annular sectionis located where the second ECC block size is equal to a length of theinner perimeter of the second annular section.
 4. Method as claimed inclaim 3, characterized in that the ECC block in the first annularsection is recorded using a first error correction code and the ECCblock in the second annular section is recorded using a second errorcorrection code and that the first error correcting code provides aerror correction capability equal to the second error correction code.5. Recorder for recording information on a record carrier comprising afirst annular section with an outer perimeter comprising an first ECCblock with a size and a second annular section with an inner perimeteradjacent to the outer perimeter of the first annular section, the secondannular section comprising a second ECC block with a size where the sizeof the second ECC block is larger than the size of the first ECC block,the recorder comprising error correction means coupled to processormeans coupled to writing means characterized in that the processor meansis operative to position the outer perimeter of the first annularsection where the second ECC block size is equal to a length of theinner perimeter of the second annular section by providing ECC blocks tothe writing means
 6. Recorder as claimed in claim 5, characterized inthat the processor are arranged to receive an first ECC block with afirst error correction code from the error correction means whenrecording the first ECC block in the first annular section and processormeans is further arranged to receive a second ECC block with a seconderror correction code from the error correction means when recording thesecond ECC block in the second annular section and that the errorcorrection capability of the first error correction code is equal to thesecond error correcting code.